Praseodymium, Atomic Number: 59. If you've ever welded metal, thank praseodymium that you can still see. Praseodymium is mixed with its periodic next-door neighbor, neodymium, to create didymium glass ...

Light REE’s are made up of the first seven elements of the lanthanide series – Lanthanum (La, atomic number 57), Cerium (Ce, atomic number 58), Praseodymium (Pr, atomic number 59), Neodymium ...

Carbon atoms have six protons, so its atomic number is six. Elements also each have a unique atomic mass. The atom's mass primarily comes from the protons and neutrons in the atom's nucleus.